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Los Angeles Conservancy Historic Preservation Awards

2005 Historic Preservation Awards

Project Summary: The Gamble House Conservation Project


The David B. Gamble House, comprising main residence and garage structures designed for David and Mary Gamble of the Proctor and Gamble Company, is listed by the United States Department of the Interior as a National Historic Landmark. As such, the site is also listed on the National Register of Historic Places.

Although the Greenes were unique artists, the architectural concepts embodied by The Gamble House fit meaningfully into the stream of ideas and aesthetics which flowed through Europe and the new world in the nineteenth and twentieth centuries. Among those are the appreciation for and appropriate use of natural materials, the expression of function in the usage and relationship of materials and elements, the liberation of space and organization of living activities, and the relationship of houses and the spaces within them to the land and landscapes around them.

The Gamble House represents a high-water mark of the “craftsman” architectural idiom which spread through neighborhoods across the country, and especially in California, from the turn of the twentieth century through about 1920. An exceptionally high level of creative design and careful craftsmanship were consciously brought to bear on a broad range of carefully selected materials—including many types of exotic and domestic woods, iridescent leaded art glass, varied examples of masonry, and other materials—to produce a work of enduring artistic beauty. The architecture of The Gamble House is especially distinctive and significant for its straightforward, unadorned expression of these materials, and for its open arrangement of living spaces with numerous links to sleeping porches and terraces to take maximum advantage of the mild climate of the region. Indeed, The Gamble House is recognized as an essential expression of Southern California life.


Type Of Project:
The project criteria are the Secretary of the Interior’s Standards for Preservation and the Ethics of the American Institute for Conservation; in this context the project is best characterized as a “preservation and conservation” project.

Scope Of The Project:
Preservation Philosophy
The project criteria are the Secretary of the Interior’s Standards for Preservation and the Ethics of the American Institute for Conservation. The preparation of a Historic Structure Report completed in 2000 with support from the Getty Grant Program confirmed that the property is internationally significant, representing the high water mark of the American Arts and Crafts movement. The report also confirmed that the site structures as found retain a very high level of integrity; in general existing materials and finishes are significant. Therefore, the project philosophy is long term protection and preservation by applying architectural conservation standards of assessment, documentation, and treatment.

Impetus For The Project
The Gamble House has been well supported and cared-for since becoming a public institution in the 1960s. However, Edward R. Bosley, Director of the property for the last decade, and the Board of Overseers, with strong leadership from the late James N. Gamble, recognized the need for an assessment of the condition of the house and a comprehensive, long term outlook for preservation of a fragile wood structure. The first step was funding and completing a Historic Structure Report during the period from 1997 to 2000. The Historic Structure Report provided detailed documentation of conditions, and categories of recommended treatment that ranged from training of staff and housekeeping to long term preservation planning goals to assure that the house and garage will be intact for another century and beyond. One of those categories of treatment, “preservation,” provided a list of recommended treatments that became the scope of work for immediate and short term needs.

During the period from 2000-2003, The Gamble House and its consultants translated the work plan to a list of work items with cost estimates for fundraising and review. The approaches, methods, and materials of treatment were refined during reviews by the Getty Grant program staff, outside peer reviewers (including Getty Museum conservation staff and the late Martin Weaver), California State Office of Historic Preservation, City of Pasadena, and National Park Service. By 2003, more than $3,000,000 had been raised from private and public sources during the preparation of construction drawings and specifications. The work was completed in the fall of 2004. One part of the work, seismic strengthening, was completed earlier on a faster track because the construction was discreet, it was fully funded by a FEMA grant, and the need was urgent.

Use Of The Structure
The Gamble House, USC, functions primarily as a historic house museum for the preservation, presentation, and interpretation of the architecture and design of Charles and Henry Greene in the context of the American Arts and Crafts movement. The house and garage are themselves artifacts, being the most important items in a collection that includes most of the original furnishings designed by the architects for the house and important architectural art glazing in windows and doors. The garage is used primarily for supporting the public tour program and houses a book store whose profits support the operation and maintenance of the property.

People It Serves
The Gamble House, USC, serves the citizens and children of Pasadena, the faculty and students of the University of Southern California, and scholars and visitors from the United States and the world. Visiting hours and tour group sizes are limited in order to protect the house; nevertheless, approximately 30,000 people tour every year during regularly scheduled tours four days of every week, or specially scheduled tours for groups. Thousands of school children have visited as part of specially scheduled tours or the youth docent program where trained Pasadena school children lead regularly scheduled tours for groups of children.

The Gamble House staff, Docents, and Friends are an institution that provides research and education. Former Director Randall Makinson and current Director Edward R. Bosley are well-published authors and frequent lecturers. There is a full time curator on the staff in addition to the Director, and a professional archivist cares for the Greene and Greene archives at the Huntington Library. The Gamble House presents an endowed annual lecture series to the public featuring prominent scholars. Edward R. Bosley led the effort to fund, produce, and bring together Avery Art and Architecture Library at Columbia University, the Environmental Design Archives at the University of California in Berkeley, and USC’s Greene & Greene Archives at the Huntington Library in a Virtual Greene & Greene archive that provides easy access via the internet most of the Greene & Greene archival material that is available in the United States.

Portions Of The Property Affected:
Structural Strengthening
Flat steel plates installed in the basement in order to connect the wood framed house to the brick basement walls that support the structure. The number and location of the plates were calculated based on the needed “hold-down” resistance to seismic forces, after subtracting the hold-down capacity of the iron rod foundation anchors installed during original construction and discovered during the Historic Structure Report investigation. The structural engineer designed the plates to be compatible in scale and shape with other original iron work. The project conservator finished the metal plates with a passivating agent that gives the plates a stable dark brown finish (“patina”) that is compatible with the original iron straps found in the house. No materials or finishes were cut or removed except for the holes that received the anchors and bolts.

Light steel frames were designed and installed with steel lag screws at two locations in the attic in order to strengthen the weakness in the outside walls where large louvered openings are found under roof gables.

Roof Replacement
A twenty-year-old built-up composition roof with mineral surfaced cap sheet had begun to fail. With the construction history of a series of roofing replacements available from the Historic Structure Report, and the assistance of a roofing consultant, the project team studied the alternatives available for built-up roofs. There is no sample available of the proprietary “Malthoid” product specified for the original construction; that roof’s early failure is documented in archival papers. The replacement roof was specified, as have subsequent replacements, to be visually compatible contemporary product with the original design while providing a safe and durable roof—a high priority for protection of the property. Products that used hot tar application rather than “torch-down” application were specified in order to eliminate the need for open flames on the roof applied against wood and inaccessible cavities and spaces behind the wood. The layout pattern of roll roofing at the cap sheet was considered with respect to durability, and delineated on the roof plan in order to illustrate precisely the visual pattern to be installed.

Old lead flashings were found at some roof-to-wall and chimney connections. Most of these flashings were labeled and removed to storage due to cracks and punctures. The roof consultant and project architect considered and then detailed extensively the addition of metal flashings (copper and lead-coated copper) that were added at invisible locations under roofing or locations that are not visible to visitors in order to substantially improved protection against leaks and lengthen the cycles of roof replacement (note that the roof replacement activity itself is potentially damaging due to the movement of crews and materials near the house).

Exterior Wood And Wood Finishes
The philosophy and methods of treatment of exterior wood surfaces was the most thoroughly considered part of the work. Exterior wood and wood finishes were categorized into thirteen conditions by observation. A sample of each condition was studied by the project scientist using laboratory methods. The architectural conservator made findings of condition and treatment recommendations with the team based on lab reports and observation of as-found finishes. In general, some treatment was necessary because of the deteriorating condition of wood shakes (strongly associated with heat and light), in particular, which was causing the failure of the paint on the shakes. It was found that the 1930s paint was originally dark green, much like the original dark green Cabot stain found on protected original shakes. That paint helped to protect the wood surfaces. The as-found condition of the walls exhibits the natural condition of the house as it ages in an environment of heat, light, and water.

In general, the exterior wood surfaces were not “restored” to the finish or appearance of the 1908 conditions. Restoration would have required removal of 1930s paint and original plant-based creosote dip to recover a bare wood surface for refinishing with new materials intended to emulate the original materials. This methodology would have destroyed the “history” of finishes, has unavoidable impacts on the surface profile of the wood, and resets the clock to an almost-new appearance that will immediately “age,” setting up a potentially destructive cycle of refinishing.

The ultimate objectives after thorough consideration were to conserve the wood, retain the history of existing finishes, avoid treatments that damage the wood, retain the variations in finish appearance that reflect the natural conditions of the building and site, and use materials and methods that are optimally reversible and/or re-treatable. Painted wood surfaces were cleaned; a clear resin-based wood protectant was applied that consolidates and protects failing wood material while consolidating the deteriorating paint. The treated paint surfaces darkened and recovered much of the original dark, cool green hue. Grimy, oily, unpainted surfaces such as windows, window screen frames, and porch posts and railings were “cleaned” using a gentle stripper (N-methyl pyrolidone) that does not profile the surface grain of wood or leave behind corrosive chemicals, before application of wood protectant. There were many small special condition areas that received variations on these treatments, including application of tinting where paint had been previously removed in past years using less gentle methods. All of this work was supervised in the field by the project’s consulting architectural conservator, who became a subcontractor in order to bring hands-on, artful consideration to every surface. A negligible number of damaged wood shakes were replaced with vintage shakes of matching species and cure.

The visual results of these treatments reversed the pre-construction color and value relationships in the house to those designed by the architects; i.e., before treatment the walls were blanched to a yellowish green hue and wood trims were dark brown; after conservation the walls returned to a darker, cool green hue, while windows, trims, and porches became natural yellow and rich brown. Nevertheless, the variations in surface tone that reflect sun exposure and water movement are still perceptible. The appearance of the house and garage will slowly turn towards the pre-treatment appearance, but those treatments were extremely gentle, and re-treatment is feasible and gentle.

Exterior Wood Repairs
The Gamble House and Garage buildings have a history of fungal damage (dry rot) at many exterior gable beams and rafter tails. More than twenty years ago a previous campaign used epoxy fillers to replace rotten wood on the house, and used Dutchman patches to replace some rafter tails on the garage. The investigation during the preparation of the Historic Structure Report found substantial new dry rot, and rot hidden below the earlier epoxy patches.

The old epoxy fillers and “punky” wood were removed, literally with the use of dental picks where appropriate, in order to retain as much original good material in place as possible. Remaining wood surfaces were treated with borates (borates are an effective, nontoxic fungicide) in solution, liquid epoxy consolidants at the interface, and borates in gel form injected in small diameter holes in areas of infection. New, more permeable epoxy fillers were used to replace lost wood. The replacement epoxy was tinted with stable mineral-based artists pigments and sculpted at the surface to blend with the tone and texture of adjacent wood; finally semitransparent stains were applied, adjusted to the tone of local wood. The epoxy filler is an inauthentic material, but it is easily identifiable at close range, and provides a visually compatible presentation to visitors at the ground level.

The Gamble House administration also raised funds and set aside an endowment for maintenance of the house, in addition to the funds used for this particular project. Rafter tail condition is a good example of a situation where periodic inspection by a qualified conservator or architect is needed in order to retreat if required.

Subterranean Waterproofing
There is efflorescence of salts at the interior of brick basement walls, some of which are finished with gypsum plaster. In particular areas the plaster is damaged. Some unfinished brick walls have failing lime mortar, and spalling brick faces. The project scope was designed to eliminate the sources of exterior water at or below grade wherever feasible.

Exterior foundation walls were excavated where they are accessible, down to the bottom of the footings. A footing drainage system and outside-applied wall membranes were installed. The decorative fish pond and tree well at the west terrace were suspected of channeling water to the west basement wall; excavation proved the point. Membranes, repairs, and drains were installed to take surface rainwater and subterranean moisture away from the west side of the house.

Compliance With The Secretary Of The Interior’s Standards
The project was reviewed and found to conform to the Secretary of the Interior’s Standards for the Treatment of Historic Properties by the staff and commissions of the City of Pasadena (a Certified Local Government), the California Office of Historic Preservation, the Federal Emergency Management Administration, and the National Park Service. These reviews were conditions of local and state regulations, a California Heritage Fund Grant, a FEMA grant, and a Save America’s Treasures grant.


The prominence of the project and the multiple reviewers and funding sources created a welcome but very close scrutiny of the project planning and implementation. The current work required at least seven years of assessment, analysis, planning, review, and fundraising prior to the start of construction, with the exception of seismic strengthening.

The vulnerability of the Gamble House to mechanical and fire damage during construction made the writing and implementation of a protection plan a critical part of the project. Crew training for safety and corrective action was required throughout the construction. The scaffolding was laid out on the site plan for the contractor; scaffolding could not be supported by the existing structures, and was held a clear distance away from the structures. A fire and blast shield was built the full height of the house at the southeast corner during the period that hot tar was being stored and heated by compressed gas for re-roofing; the gas containers were removed from the site when not being used.

Public tours were maintained throughout the period of construction, raising the standards for safety and appearance. There was full fencing and overhead protection as passages, paths of access were altered. The site was extremely clean and uncluttered, 24 hours per day. Fences, scaffolding boards, the construction office, and construction storage container were all painted dark brown for compatibility with the Gamble House and its setting.


Protection of the integrity of the Gamble House, while conserving it as an artifact for future generations is the primary public benefit of this project.

The Gamble House, USC, in keeping with the intent of support grants received from the Getty Grant Program et al., will make information about the assessments and treatment methods and materials available to everyone—professionals, scholars, and homeowners. Other Greene and Greene properties and stewards of buildings with significant wood exteriors will benefit from this information.

Locally, The Gamble House, USC, is taken for granted as an important site with excellent staff, support organizations, and operations. The Director, USC, staff, and City of Pasadena deserve special recognition for starting the planning process that led to this project and will guide the site in the future. The Gamble House, USC, deserves special recognition for its research and education programs that reach far beyond the walls of the Gamble House. The Gamble House, USC, deserves special recognition for maintaining and demonstrating to others the highest level of objectives and performance in all of these activities.


The Gamble House Conservation Project
The Gamble House, USC
Edward R. Bosley, James N. Gamble Director